1. Field of the Invention
The present invention relates generally to systems and methods for network switching, and more particularly to efficient call routing in a telecommunications system.
2. Related Art
A conventional telecommunications network comprises three basic components: user terminals (for example, telephones), communications busses (also known as links; for example, telephone lines) and nodes. The nodes are used to selectively connect the user terminals via the links. A node is a functional entity employed to route a call, not a physical entity. Therefore, the correspondence between nodes and physical switches is not necessarily one-to-one.
In a typical telephone call, when an originating end user (hereinafter a "caller") places a call to a terminating end user (hereinafter a "called party"), the network creates a communications path by connecting the caller's user terminal (for example, a telephone) to the called party's user terminal, via a number of nodes, using communications busses. Occasionally, the called party will be busy, and will place the call "on hold" and/or in a queue. For example, this often happens when calling toll-free numbers. When this happens, the caller is faced with two options: he can (1) wait in the queue for his call to be answered, or (2) disconnect (that is, "hang up"). If the caller waits, his time is wasted for an unknown duration because he cannot make other calls. If the caller hangs up, he loses his place in the queue and the time he has already spent in the queue is wasted.
One approach to the problem is to provide the caller with a telephone having two separate lines and a "hold" function. When the caller is placed on "hold," he can then place that call on hold and make a call from the telephone's second line. The primary disadvantage of this terminal-based approach is that it requires a specialized telephone and a second phone line. Both items come at a significant cost to the caller.
Another approach is to implement a second phone line in a private branch exchange (PBX). The caller can then access the second line and the hold function by entering particular codes (for example, "*7" or the like) on the user's telephone. While this approach eliminates the need for a specialized telephone, it still requires that a separate second call be placed, requiring twice the network resources.
What is needed is a system and method to permit a caller to place other calls while retaining his original call, without requiring a special telephone or a separate second call.